608 THE ANATOMY OF THE STEM OF THE PAPAVERACE^E. 



Fig. 4. Longitudinal section of the phloem, showing sieve tubes with callus and laticiferous cells 

 with perforations (H). 



,, 5. Longitudinal section, showing sieve tubes and companion cells (H). 

 „ 6. Transverse section of vascular bundle (H). 



,, 7. Longitudinal section of phloem, showing laticiferous tubes (H). 

 ,, 8. Transverse section of primary xylem, showing conjunctive parenchyma (H). 



,, 9. Transverse section of secondary xylem, showing wood fibres replacing conjunctive parenchyma (H). 



,, 10. Transverse section of vascular system at the base of the stem, showing concentric bundles (L). 



,, 11 (on Plate II). Transverse section, concentric bundle from stem base (Hj. 



„ 12, a-f. Successive transverse sections, showing the mode of entry of the leaf-trace (L). 



,, 13. Transverse section of stem of Papaver somniferum (L). 



„ 14. Laticiferous cells of A rgemone mexicana (H). 



,, 15. Superficial layers of the stem of Chelidonium majus (H). 



,, 15a. Transverse section of stem of Chelido?iium majus, diagrammatic (L). 



„ 16. Superficial layers of the stem of Glaucium corniculatum (H). 



,, 17. Superficial layers of the stem of Bocconia microcarpa (H). 



Plate II. 



Fig. 18. Bordered pits in surface and section from the xylem of Bocconia microcarpa (H). 



,, 19. Transverse section of stem of Eschscholzia calif omica (L). 



,, 20. Peripheral layers of the stem (H). 



„ 21. Transverse section of peripheral layers and vascular bundle of Hypecoum grandiflorum (H). 



„ 22. Xylem elements containing latex (H). 



,, 23. Transverse section of peripheral layers and vascular bundle of Dicentra formosa (H). 



,, 24. Transverse section of stem of Adlumia cirrhosa (L). 



Plate III. 



Fig. 25. Cortical region of the stem of Romneya trichocalyx (H). 



,, 26. Epidermis and subepidermis of Corydalis racemosa (H). 



,, 27. Cells with folded walls on the inner margin of the vascular bundles (H). 



,, 28. Fusion of the vascular bundles in the stem base of Papaver orientale (L). 



„ 29. Medullary cambium in the stem base (L). 



., 30. Formation of secondary xylem and phloem from the medullary cambium (L). 



,, 31, a, b, c. Successive stages in the entry of the leaf-trace of Argemone mexicana (L). 



„ 32, a, b, c. Successive stages in the entry of the leaf-trace of Papaver dubium (L). 



„ 33, a, b, c. Successive stages in the entry of the leaf-trace of Papaver glaucium (L). 



,, 34, 35. Types of leaf-trace entry in Papaver lateritivm (L). 



,, 36, a, b, c. Entry of leaf-traces in Argemone mexicana (L). 



,, 37. Entry of leaf-trace in Bocconia microcarpa (L). 



,, 38. Entry of leaf-trace in Adlumia cirrliosa (L). 



,, 39. Entry of leaf-trace in Corydalis racemosa (L). 



